The invention relates to a filtration plate for a particle filter which serves to separate particles from an exhaust gas flow of an internal combustion engine. Furthermore, the invention relates to a particle filter for separating particles from an exhaust gas flow of an internal combustion engine.
German patent document DE 42 34 930 A1 discloses a filter for separating contaminants from exhaust gases. The filter has a filter body having a multiplicity of filtration plates. The filter plates are composed of sintered metal powder and are arranged in such a way that they form a multiplicity of flow channels which lie next to one another. The individual filtration plates are stamped in a wave shape and are flowed through in the longitudinal direction. This wave shape of the filtration plates leads to longitudinal channels which are delimited in each case with respect to one another, and which can become clogged with ash very quickly and impair the action of the filter. Furthermore, the channels which are stamped in such a way result in a highly directed flow which prevents a distribution above the plane of the filtration plates and therefore leads to an increased exhaust gas back pressure. A further disadvantage of the known filtration plates lies in their low rigidity which makes handling considerably difficult and which can impair their service life.
International patent application publication no. WO 02/102494 A1 discloses a further particle filter. Here, a plurality of filter pockets are arranged in a star shape around the circumference of a central hole. The filter pockets have a triangular cross section into which a spacer element is inserted. The space element is intended to prevent a deformation of the filter pockets as a result of the exhaust gas pressure. This spacer element which is also called a “spacer” is, however, an additional component which represents an additional expenditure during the manufacture of the particle filter. Furthermore, it must be ensured in the design of the spacer element that it does not represent an obstacle for the exhaust gas flow, as it would otherwise cause an increase in the exhaust gas back pressure.
In the particle filter according to German patent document no. DE 101 28 938 A1, the filtration plates have respective embossments which are intended to make the filtration plates support one another.
The filter plates are usually installed into a filter housing as a filter body with a defined pre-stress and, in a horizontal installation position. Because the filtration plates are additionally pressed together by their inherent weight and by the exhaust gas pressure, the space which is situated between the filtration plates can become smaller very easily and can even be eliminated completely. This can result in considerable impediment to the flow, which cannot be prevented reliably even with the solution according to German patent document no. DE 101 28 938 A1.
It is therefore an object of the present invention to provide a filtration plate for a particle filter such that, when the filtration plate forms an inflow or outflow channel with a further filtration plate, there is always an intermediate space which is sufficient for satisfactory throughflow. Furthermore, the design of the filtration plate preferably represents a small obstacle for the exhaust gas flow.
These and other objects and advantages are achieved by the filtration plate according to the invention, which utilizes a spacer element having an inner elevation or depression which extends away from the surface region, and an outer depression or elevation which surrounds the inner elevation or depression and extends away from the surface region in the opposite direction to the inner elevation or depression. This results in a spacer element which extends on both sides of the surface region of the filtration plate. Thus, if two or more of these filtration plates are combined to form a filter body, mutual contact of the spacer elements is always ensured. In this way, filter plates which are arranged adjacently to one another are prevented from being pressed together, and the ability for throughflow of the filtration plates is ensured at all times.
This is true, in particular, when a multiplicity of spacer elements are distributed over the surface region.
Here, a spacer element is understood to encompass a defined region of a respective filtration plate, which maintains a spacing of the adjacent filtration plates on account of its structure.
According to one embodiment of the invention, a plurality of filtration plates which are arranged next to one another and define a particle filter for separating particles from an exhaust gas flow of an internal combustion engine.
A particle filter of this type utilizes all the advantages of the filtration plate according to the invention, with the result that the ability for flowthrough of the inflow and outflow channels is always ensured.
In one embodiment of the particle filter according to the invention, the spacer elements can be arranged on the filtration plates in such a way that the spacer elements of adjacent filtration plates are in mutual contact, and such that the filtration plates have an arrangement with respect to one another whereby an inner elevation of one filtration plate contacts the inner depression of the adjacent filtration plate, or an outer depression of one filtration plate contacts the outer elevation of the adjacent filtration plate.
A configuration of this type ensures that the abovementioned advantages of the filtration plates according to the invention are utilized advantageously by the particle filter according to the invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.